The present invention relates to an electronic device, an electronically controlled mechanical timepiece, and a control method therefore, and more particularly, to an electronic device having a mechanical energy source, a generator that is driven by the mechanical energy source, generates induced electric power, and outputs electrical energy, an electric storage unit for storing the electrical energy output from the generator, and a rotation control unit that is driven by the electrical energy supplied from the electric storing unit and controls the rotation cycle of the generator; an electronically controlled mechanical timepiece; and a control method therefor.
As an electronically controlled mechanical timepiece that converts the mechanical energy produced when a mainspring is unwound into electrical energy by a generator, uses the electrical energy to actuate a rotation control unit so as to control the value of a current passing through a coil of the generator, thereby accurately driving the hands fixed to a wheel train to accurately display time, there has been known an electronically controlled mechanical timepiece disclosed in Japanese Examined Patent Application Publication No. 7-119812.
In the invention disclosed in the Japanese Examined Patent Application Publication No. 7-119812, brake-OFF control is conducted at each of a plurality of first time points that periodically take place at the cycle of a reference signal from a crystal oscillator or the like, and brake-ON control is conducted at a second time point spaced away the first time point in the cycle of the reference signal. The brake-ON control and the brake-OFF control are always carried out in one cycle of a reference cycle.
However, the brake-ON control begun at the second time point of a reference cycle is forcibly switched to the brake-OFF control at the first time point of the next reference cycle regardless of the rotation state of the generator. This has been posing a problem in that a sufficient brake amount cannot be supplied, depending on the state, and much time is required before speed control is completed.
Furthermore, in addition to the electronically controlled mechanical timepieces, in a variety of electronic devices, such as music boxes, metronomes, toys, and electric razors, that have components rotatively controlled by mechanical energy sources, such as springs or elastic, there has always been a demand for improved accuracy of moving parts, e.g., the operations of the drums of music boxes or the pendulums of metronomes, by conducting accurate brake control.
An object of the present invention is to provide an electronic device capable of applying an accurate and sufficient brake amount and of achieving improved responsiveness of speed control and stable control, an electronically controlled mechanical timepiece, and a control method therefor.
An electronic device of the present invention is equipped with a mechanical energy source, a generator that is driven by the mechanical energy source, generates induced electric power, and supplies electrical energy, and a rotation control unit that is driven by the electrical energy and controls a rotation cycle of the generator, wherein the rotation control unit is provided with a brake control unit that compares a reference signal issued based on a signal from a time standard source with a rotation detection signal based on the rotation cycle of the generator thereby to adjust a braking time of the generator, and a brake amount correcting unit for correcting the braking time set by the brake control unit on the basis of the rotation cycle of the generator.
At this time, preferably, the brake amount correcting unit corrects the braking time by making the braking time shorter than the time set by the brake control unit if the rotation cycle of the generator is later (or longer: the same will apply hereinafter) than a predetermined range based on the cycle of the reference signal.
The brake amount correcting unit may correct the braking time by making the braking time longer than the time set by the brake control unit if the rotation cycle of the generator is earlier (or shorter: the same will apply hereinafter) than the predetermined range.
Preferably, the brake amount correcting unit corrects the braking time by making the braking time shorter than the time set by the brake control unit if the rotation cycle of the generator is later than a predetermined range based on the cycle of the reference signal, or by making the braking time longer than the time set by the brake control unit if the rotation cycle of the generator is earlier than the predetermined range.
In the electronic device in accordance with the present invention, the generator is driven by a mechanical energy source, such as a spring, and the number of rotations of a rotor is controlled by applying a brake to the generator by a rotation control unit.
At this time, if the rotation cycle of the generator is close to the reference signal cycle, that is, if the rotation cycle is based on the reference signal cycle and stays within a predetermined range, then the brake control is carried out on the basis of the braking time set by the comparison between the reference signal and a rotation detection signal performed by the brake control unit.
Furthermore, if the rotation cycle of the generator significantly deviates from the reference signal cycle, then the braking time, i.e., the brake amount, is adjusted on the basis of the rotation cycle. For example, if the rotation cycle is shorter than the reference signal cycle, then the braking time is made longer than the time set at the brake control unit so as to suppress the rotational speed of the generator thereby causing the rotation cycle to quickly approach the reference signal. If the rotation cycle is longer than the reference signal cycle, then the rotational speed of the generator is increased by making the braking time shorter than the time set at the brake control unit so as to increase the rotational speed of the generator, thereby causing the rotation cycle to quickly approach the reference signal.
With this arrangement, optimum brake control is conducted on the basis of the rotation cycle of the generator regardless of the reference cycle; hence, a secure, sufficient brake amount is applied, and the responsiveness in speed control can be enhanced, as compared with the case where the brake-ON control and the brake-OFF control are always carried out in every cycle of the reference cycle. Thus, variations in the rotation cycle of a rotor of a generator can be reduced, allowing the generator to stably rotate at a substantially constant speed.
The time during which the brake amount correcting unit adjusts the braking time may be set, for example, in one level or more beforehand according to the rotation cycle of the generator, or may be set so that it is continuously changed according to the rotation cycle at that point.
The correction time for correcting the braking time may be in one level (fixed); however, setting the correction time in one level or more, preferably two levels or more, on the basis of the magnitude of the rotation cycle, i.e., the displacement from the reference cycle, makes it possible to bring the rotation cycle of the generator close to the reference cycle more quickly by extending the correction time even in case of a significant deviation from the reference cycle. Setting the correction time so that it is continuously changed according to the rotation cycle permits more detailed adjustment to be made.
Preferably, the brake control unit is provided with a count-up/down counter that receives one of the rotation detection signal and the reference signal as a count-up signal, receives the other as a count-down signal, and is configured so that if the value of the count-up/down counter is a set value or more, then a brake is applied to the generator, and if it is below the set value, then the brake applied to the generator is released.
Employing the count-up/down counter makes it possible to compare count values while counting rotation detection signals and reference signals at the same time, so that the construction will be further simpler and a difference between count values can be easily determined.
Preferably, the rotation control unit corrects the braking time made by the brake amount correcting unit only if the value of the count-up/down counter lies in a predetermined range that includes the set value.
Correcting the brake involves a shift from ON to OFF of the brake; hence, the brake cannot remain ON or OFF. For this reason, if the value on the count-up/down counter is considerably off from the vicinity of a set value that provides a threshold value of the brake control, then no brake correction is made to allow the brake to remain ON or OFF. This, for example, permits quick elimination of a cumulative error in a case where the rotation cycle considerably deviates from a reference cycle at the startup or the like of the generator.
An electronic device according to another aspect of the present invention is equipped with a mechanical energy source, a generator that is driven by the mechanical energy source, generates induced electric power, and supplies electrical energy, and a rotation control unit that is driven by the electrical energy and controls a rotation cycle of the generator, wherein the rotation control unit is equipped with a brake control unit that compares a reference signal issued on the basis of a signal from a time standard source with a rotation detection signal based on the rotation cycle of the generator thereby to adjust a high braking time during which a high brake is applied to the generator, and a brake amount correcting unit for correcting the high braking time set by the brake control unit on the basis of the rotation cycle of the generator.
At this time also, preferably, the brake amount correcting unit corrects the high braking time by making the high braking time shorter than the time set by the brake control unit if the rotation cycle of the generator is later than a predetermined range based on the cycle of the reference signal.
Furthermore, the brake amount correcting unit may correct the braking time by making the high braking time longer than the time set by the brake control unit if the rotation cycle of the generator is earlier than the predetermined range.
Preferably, the brake amount correcting unit corrects the braking time by making the high braking time shorter than the time set by the brake control unit if the rotation cycle of the generator is later than a predetermined range based on the cycle of the reference signal, or by making the high braking time longer than the time set by the brake control unit if the rotation cycle of the generator is earlier than the predetermined range.
In the present invention described above also, if the rotation cycle of the generator is close to the reference signal cycle, that is, if the rotation cycle lies in a predetermined range based on the reference signal cycle, then the brake control is conducted by the braking time set based on the comparison between the reference signal and a rotation detection signal performed by the brake control unit.
Furthermore, if the rotation cycle of the generator significantly deviates from the reference signal cycle, then the high braking time, i.e., the brake amount, is adjusted on the basis of the rotation cycle. For example, if the rotation cycle is shorter than the reference signal cycle, then the high braking time is made longer than the time set at the brake control unit so as to suppress the rotational speed of the generator thereby causing the rotation cycle to quickly approach the reference signal. If the rotation cycle is longer than the reference signal cycle, then the high braking time is made shorter than the time set at the brake control unit so as to increase the rotational speed of the generator, thereby causing the rotation cycle to quickly approach the reference signal.
With this arrangement, optimum brake control is conducted on the basis of the rotation cycle of the generator regardless of the reference cycle; hence, a secure and sufficient brake amount can be provided, and the responsiveness in speed control can be enhanced, as compared with the case where the brake-ON control and the brake-OFF control are always carried out in every cycle of the reference cycle. Thus, variations in the rotation cycle of a rotor of a generator can be reduced, allowing the generator to stably rotate at a substantially constant speed.
Preferably, the rotation control unit is equipped with a switch capable of forming a closed loop with both ends of the generator, and a chopper signal generating section that produces chopper signals of two or more types differing in at least duty ratio or frequency applied to the switch. To apply a high brake to the generator, one type of a chopper signal is applied to the switch, and in other cases, the other type of a chopper signal capable of causing the application of a brake that provides a weaker braking force than the high brake is applied to the switch.
By applying the chopper signals to the switch capable of forming the closed loop with both ends of the coil of the generator to turn the switch ON/OFF, that is, to perform choppering, the closed loop is formed with both ends of the coil of the generator thereby to apply a short brake, and energy is stored in the coil of the generator when the switch is turned ON. When the switch is turned OFF, the closed loop state is cleared, and the generator is actuated. Since there is the energy stored in the coil, an electromotive voltage is increased. Hence, carrying out control by the choppering when applying the high brake to the generator, the drop in the generated power at braking can be made up for by the increase in the electromotive voltage at the switching OFF. This makes it possible to configure an electronic device that is capable of increasing braking torque (brake torque) while suppressing a drop in the generated power at the same time, prolonging the lasting time.
Charging voltage can be further increased by carrying out the control also by choppering when applying the low brake.
The closed loop state that is set when the switch is turned ON may be a state wherein the braking force applied to the generator is greater than that applied in a non-closed loop state. A resistance element or the like may be provided between, for example, the switch and the generator on a circuit designed to have a closed loop.
The time during which the brake amount correcting unit adjusts the braking time may be set, for example, in one level or more beforehand according to the rotation cycle of the generator, or may be set so that it continuously changes according to the rotation cycle at that point.
Setting the correction time of the brake in one level or more, preferably two levels or more, on the basis of the magnitude of the rotation cycle, i.e., the displacement from the reference cycle, makes it possible to bring the rotation cycle of the generator close to the reference cycle more quickly by extending the correction time in case of a significant deviation from the reference cycle. Setting the correction time so that it is continuously changed according to the rotation cycle permits more detailed adjustment to be made.
The brake control unit is provided with a count-up/down counter that receives one of the rotation detection signal and the reference signal as a count-up signal, and receives the other as a count-down signal, and is configured so that if the value of the count-up/down counter is a set value or more, then the high brake is applied to the generator, or if it is below the set value, then the low brake is applied to the generator.
Employing the count-up/down counter makes it possible to compare count values while counting rotation detection signals and reference signals at the same time, so that the construction will be further simpler and a difference between count values can be easily determined.
The brake amount correcting unit may correct the high braking time only if the value of the count-up/down counter lies in a predetermined range that includes the set value.
Correcting the brake involves a shift from the high brake to the low brake; hence, it is impossible to keep on applying the high brake or the low brake. For this reason, if the value on the count-up/down counter is considerably off from the vicinity of a set value that provides a threshold value of the brake control, that is, further outside the range in which the correction is made, then no brake correction is made so as to allow the application of the high brake or the low brake to be continued. This, for example, permits quick elimination of a cumulative error in a case where the rotation cycle considerably deviates from a reference cycle at the startup or the like of the generator.
The electronic device is preferably a timing device, a music box, or a metronome. These will be able to provide clocking devices, music boxes, or metronomes that have prolonged lasting time, and are rotatively controlled with accuracy.
An electronically controlled mechanical timepiece according to the present invention is characterized in that it is provided with the electronic device described above, and hands that are rotated, together with driving of the generator, by the mechanical energy source of the electronic device and subjected to speed control by the rotation control unit.
To be more specific, the electronically controlled mechanical timepiece is provided with the mechanical energy source, the generator that is driven by the mechanical energy source coupled through the intermediary of an energy transmitting unit, such as a wheel train, and generates induced electric power to supply electrical energy, hands coupled to the energy transmitting unit, such as the wheel train, and a rotation control unit that is driven by the electrical energy to control the rotation cycle of the generator, wherein the rotation control unit is equipped with a brake control unit that compares a reference signal issued based on a signal from a time standard source with a rotation detection signal based on the rotation cycle of the generator to set a braking time of the generator, and a brake amount correcting unit for correcting the braking time set by the brake control unit on the basis of the rotation cycle of the generator.
The electronically controlled mechanical timepiece is provided with the mechanical energy source, the generator that is driven by the mechanical energy source coupled through the intermediary of an energy transmitting unit, such as a wheel train, and generates induced electric power to supply electrical energy, hands coupled to the energy transmitting unit, such as the wheel train, and a rotation control unit that is driven by the electrical energy to control the rotation cycle of the generator, the rotation control unit may be equipped with a brake control unit that compares a reference signal issued based on a signal from a time standard source with a rotation detection signal based on the rotation cycle of the generator to set a high braking time during which the high brake is applied to the generator, and a brake amount correcting unit for correcting the braking time set by the brake control unit on the basis of the rotation cycle of the generator.
According to the electronically controlled mechanical timepiece, variations in the rotation cycle of a rotor of a generator can be reduced, allowing the generator to rotate at a substantially constant speed, so that the swing of the needles of the hands operated by being interlocked with the rotation of the rotor can be reduced. Moreover, the brake torque of the generator can be increased while suppressing a drop in the generated power, so that a timepiece with high accuracy and prolonged lasting time can be provided.
The invention according to an aspect of the present invention is a control method for an electronic device provided with a mechanical energy source, a generator that is driven by the mechanical energy source, generates induced electric power, and supplies electrical energy, and a rotation control unit that is driven by the electrical energy and controls a rotation cycle of the generator, wherein a braking time of the generator is adjusted by comparing a reference signal issued based on a signal from a time standard source with a rotation detection signal based on the rotation cycle of the generator to adjust the braking time of the generator, and the braking time set by the brake control unit is corrected on the basis of the rotation cycle of the generator.
The invention according to another aspect of the present invention is a control method for an electronic device provided with a mechanical energy source, a generator that is driven by the mechanical energy source, generates induced electric power, and supplies electrical energy, and a rotation control unit that is driven by the electrical energy and controls a rotation cycle of the generator, wherein a high braking time during which high brake is applied to the generator is adjusted by comparing a reference signal issued based on a signal from a time standard source with a rotation detection signal based on the rotation cycle of the generator, and the high braking time set by the brake control unit is corrected on the basis of the rotation cycle of the generator.
The invention according to another aspect of the present invention is a control method for an electronically controlled mechanical timepiece provided with a mechanical energy source, a generator that is driven by the mechanical energy source coupled through the intermediary of an energy transmitting unit and generates induced electric power to supply electrical energy, hands coupled to the energy transmitting unit, and a rotation control unit that is driven by the electrical energy to control the rotation cycle of the generator, wherein a reference signal issued based on a signal from a time standard source is compared with a rotation detection signal based on the rotation cycle of the generator so as to adjust a braking time of the generator, and the braking time set by the brake control unit is corrected on the basis of the rotation cycle of the generator.
The invention according to another aspect of the present invention is a control method for an electronically controlled mechanical timepiece provided with a mechanical energy source, a generator that is driven by the mechanical energy source coupled through the intermediary of an energy transmitting unit and generates induced electric power to supply electrical energy, hands coupled to the energy transmitting unit, and a rotation control unit that is driven by the electrical energy to control the rotation cycle of the generator, wherein a reference signal issued based on a signal from a time standard source is compared with a rotation detection signal based on the rotation cycle of the generator so as to adjust a high braking time during which a high brake is applied to the generator, and the high braking time set by the brake control unit is corrected on the basis of the rotation cycle of the generator.
In each of these aspects of the present invention, to correct a braking time, it is preferable that, if the rotation cycle of the generator is later than a predetermined range based on the cycle of the reference signal, then the braking time is made shorter than the time set by comparing the reference signal and the rotation detection signal, or if the rotation cycle of the generator is earlier than the predetermined range, then the braking time is made longer than the time set by comparing the reference signal and the rotation detection signal, thereby correcting the braking time.
According to the control methods, if the rotation cycle of the generator is close to a reference signal cycle, that is, if the rotation cycle lies within a predetermined range based the reference signal cycle, then the comparison between the reference signal and the rotation detection signal is performed to carry out the brake control.
If the rotation cycle of the generator significantly deviates from the reference signal cycle, that is, if the rotation cycle lies outside the predetermined range based on the reference signal cycle, then the braking time or the high braking time is adjusted on the basis of the rotation cycle.
With this arrangement, optimum brake control is conducted on the basis of the rotation cycle of the generator regardless of the reference cycle; hence, a secure, sufficient brake amount is applied, and the responsiveness in speed control can be enhanced, as compared with the case where the brake-ON control and the brake-OFF control are always carried out in every cycle of the reference cycle. Thus, variations in the rotation cycle of a rotor of a generator can be reduced, allowing the generator to stably rotate at a substantially constant speed. Accordingly, variations in the rotation cycle of the rotor of a generator can be reduced, and the generator can be rotated at a substantially constant speed, permitting an electronic device and an electronically controlled mechanical timepiece featuring smooth operation to be achieved.